Papillary microcarcinomas of the thyroid gland and immunohistochemical analysis of expression of p53 protein in papillary microcarcinomas

Papillary microcarcinoma of the thyroid gland: current controversies and management

PURPOSE OF REVIEW

To highlight recent advances in our understanding of the nature of micropapillary thyroid carcinoma (mPTC), its evaluation and options of management based on risk.

RECENT FINDINGS

A dramatic increase of the incidence of papillary thyroid carcinoma has been reported worldwide during recent decades, specifically those smaller than 10 mm (mPTC). Although not taking into consideration other risk factors for aggressiveness when describing tumours by their size, most of these newly diagnosed mPTC are indolent and active surveillance can be considered as valid option for their management.

SUMMARY

An increasing number of patients with mPTC will be encountered in clinical practice. Although it is difficult to assess the aggressiveness of a tumour on size criteria, less than a total thyroidectomy and active surveillance can be considered for the majority of patients with mPTC. Further trials should be performed to prove this as a valid option of management in the majority of these patients.

Thyroid Papillary Microcarcinoma: Etiology, Clinical Manifestations,Diagnosis, Follow-up, Histopathology and Prognosis

BACKGROUND

Thyroid carcinoma is the most common malignancy of the endocrine system. Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer, accounting for 70-90% of well-differentiated thyroid malignancies. Thyroid papillary microcarcinoma is a subtype of papillary carcinoma that included tumors with less than 10mm diameter. As a result of diagnostic methods improvement, prevalence of this tumor is increasing. In this study we reviewed different characteristics of tumor.

METHODS

We searched various factors about this tumor in different databases (PubMed, Ovid, Google scholar, Iran medex and SID databases, from July 2012 until August 2013), after that, the articles were classified. Data of each article were extracted and sorted in tables. Data of each factor in different articles were summarized.

RESULTS

Etiology, clinical presentation, prognosis, histopathology, follow-up, diagnosis and also age, gender, tumor size and treatment were factors about this tumor described in details here.

CONCLUSION

Awareness and better understanding of the characteristics of this tumor and manage it as an individual and valuable tumor can take an effective step in promoting public health practice.

Ultrasound findings of papillary thyroid microcarcinoma: a review of 113 consecutive cases with histopathologic correlation

Papillary thyroid microcarcinoma (PTMC) is a malignant thyroid tumor of less than 1 cm in size. Ultrasound (US) is the preferred imaging modality for PTMC. This study retrospectively evaluated the US results from 113 consecutive cases of PTMC with 127 nodules and correlated the results with the histopathologic findings. The results showed none of the PTMC nodules had a cystic element. Half of the PTMC nodules had a well-defined boundary and the remaining half had an ill-defined boundary. A percent (6.3%) of the nodules had a halo sign. Microcalcification was present in approximately half of the PTMC nodules. The cancerous tissue with a papillary structure was hypoechogenic and the amount of fibrous stroma determined whether the nodule echogenicity was heterogeneous or homogeneous. Heterogeneous echogenicity was associated with a fibrous stroma proportion of >20%. Only PTMC nodules with predominantly follicular structures containing a large proportion of colloid demonstrated isoechogenicity. Well-defined boundaries on US were associated with well-defined histologic margins, with or without the presence of an intact fibrous pseudo-capsule. A halo sign with a well-defined boundary detected by US was associated with the presence of an intact fibrous pseudo-capsule. Half of the PTMC nodules with ill-defined boundaries exhibited infiltration into the surrounding thyroid tissue, while the remaining half of the PTMC nodules with ill-defined boundaries on US presented irregular nodule margins by histology, rather than nodule infiltration. Psammoma bodies detected at a frequency ≥5 per ×200 microscopic field of view were detectable on US as microcalcifications.

Are Papillary Microcarcinomas of the Thyroid Gland Revealed by Cervical Adenopathy More Aggressive?

Therapeutic attitudes for papillary thyroid microcarcinoma (PTMC) range from observation alone to aggressive management. Clinicopathologic features, therapeutic options, and follow-up results are described in a series of PTMC revealed by cervical adenopathies. Twelve patients were enrolled in this retrospective study. They were all treated by total/near-total thyroidectomy with dissection of suspect cervical lymph nodes followed by radioactive iodine (RAI) and suppressive L-thyroxine therapies. Mean age at diagnosis was 32 years with a mean elapsed time to diagnosis of 45.3 months. Fine needle aspiration cytology and excisional biopsy of the lymph node led to a diagnosis in all cases. Cervical mass was ipsilateral to primary tumor in six patients (50%). Multifocality, bilaterality, and capsular invasion were encountered in 66.7, 66.7, and 41.7 per cent of patients, respectively. Lymph node involvement was bilateral in seven patients (58.3%) of whom thyroid foci were unilateral in two. No complications of thyroidectomy were encountered. At 60-month-follow up, no recurrence or metastasis was noted. PTMC revealed by cervical lymph node metastasis shows aggressive clinicopathologic features. They must be considered as papillary thyroid cancers and managed by total/near-total thyroidectomy with bilateral lymph node exploration followed by RAI therapy and suppressive L-thyroxine doses.

Prognostic factors affecting neck lymph node recurrence and distant metastasis in papillary microcarcinoma of the thyroid: results of a study in 445 patients

BACKGROUND

The management of thyroid papillary microcarcinoma (PMC) is controversial. Total thyroidectomy, thyroid lobectomy/isthmectomy, and even no treatment have been proposed. We investigated the clinical course and prognostic factors for disease recurrence and distant metastasis in 445 patients with PMC.

METHODS

Data from 445 patients diagnosed with PMC in the period from 1978 to 2003 were reviewed and analyzed. Total thyroidectomy was performed in 404 patients and loboisthmusectomy in 41. Neck dissection took place in 226 patients (49.7%), with 166 of only the central compartment and 60 of both the central and lateral compartments. Radioiodine ((131)I) ablation treatment was given to 389 patients.

RESULTS

Median tumor size was 7 mm (range 1-10 mm). PMC was multifocal in 156 cases (35%) and bilateral in 60 cases (13.5%). Extrathyroidal tumor extension (pT3) and neck lymph node metastasis (pN1) were present in 133 (30%) and 182 (40.9%) patients, respectively. Capsular invasion without extrathyroidal tumor extension was observed in 39 (8.7%) patients. Mean follow-up was 5.3 (range 1-26) years. Seventeen (3.8%) patients had recurrence or persistence of disease: neck recurrence (NR) in 12 (2.7%), distant metastasis (DM) in four (0.9%), NR + DM in one (0.2%). One patient (0.2%) died of the disease. Capsular invasion, extrathyroidal tumor extension (pT3), and neck lymph node metastasis at presentation (pN1) were the only independent risk factors for NR and/or DM occurrence (p < 0.05). Patients not showing these features, who were treated with loboisthmusectomy only, never experienced disease recurrence.

CONCLUSION

Total thyroidectomy seems advisable in PMC with extrathyroidal extension and neck lymph node metastasis at presentation. Capsular invasion without extrathyroidal extension may suggest aggressive tumor behavior and require radical treatment.

Apoptosis and proliferation related molecules (Bcl-2, Bax, p53, PCNA) in papillary microcarcinoma versus papillary carcinoma of the thyroid

AIM

To gain a better insight into the differences in biological behaviour between papillary microcarcinoma (PMC) and clinically evident papillary thyroid carcinoma (PTC).

METHODS

Immunohistochemical analysis of apoptosis related molecules (Bcl-2, Bax, p53) and proliferation related marker (PCNA) in 39 archival cases of PMC and 46 cases of PTC.

RESULTS

Bcl-2 and Bax were expressed in most PMCs and PTCs. The average Bcl-2 staining score did not differ significantly between PMCs and PTCs (p > 0.05), but the average Bax score was significantly lower in PMCs (p < 0.05). The Bcl-2/Bax ratio was significantly higher in PMCs than in PTCs (p < 0.05). The expression of p53 was similar in PMCs and PTCs, without a correlation with clinical data, but was associated with high Bax expression (p < 0.05) in these cases in both groups. Non-malignant tissue expressed only Bcl-2, but not p53 or Bax. PCNA expression was significantly lower (p < 0.05) in PMC than in PTC and positively correlated with tumour size (p < 0.05).

CONCLUSIONS

The higher Bcl-2/Bax ratio and lower proliferative activity in PMC suggest differences from PTC in the balance between apoptosis and proliferation. However, the presence of p53 and Bax in PMC indicates malignant potential, and thus PMC should be treated with caution.

Nodule heterogeneity as shown by size differences between the targeted nodule and the tumor in thyroidectomy specimen: a cause for a false-negative diagnosis of papillary thyroid carcinoma on fine-needle aspiration

BACKGROUND

Missed papillary thyroid carcinoma (PTC) diagnoses on fine-needle aspiration (FNA) can result from many causes. To the authors' knowledge, the issue of whether the detection of PTC is correlated with nodule heterogeneity has not been studied to date.

METHODS

The authors identified all thyroidectomy specimens with a diagnosis of PTC that had undergone at least 1 prior FNA in the study institution between 1998 and 2003. The tumor size at the time of the resection, the ultrasound (US)-determined nodule size, and other parameters were compared between the 2 groups in which PTC was or was not diagnosed on FNA.

RESULTS

Of a total of 89 specimens, 47 were diagnosed on FNA with an average tumor size of 1.7 cm and an US-determined nodule size of 2.1 cm (a difference of 0.4 cm). Forty-two specimens with a smaller average tumor size of 0.9 cm (P < .0001) and a US-determined nodule size of 2.4 cm (a difference of 1.5 cm) were missed. The differences with regard to the US-determined nodule size and tumor size between the 2 groups were significant (0.4 cm vs 1.5 cm; P < .0001). In the missed group, 29 specimens were found to have PTC foci that measured < or = 1.0 cm and 26 had a reasonable size difference (RSD; defined as a PTC size outside the range of +/-50% of the US-determined nodule size) as the indicator of the mixed nature of nodules targeted for FNA, whereas in the diagnostic group, 9 foci measured < or = 1.0 cm and 6 had RSD. There was no cytologic evidence with which to render a diagnosis of PTC on further review in the missed group.

CONCLUSIONS

The major reason for a missed diagnosis of PTC on FNA is because of inadequate tumor sampling due to the heterogeneity of the nodule targeted for FNA. This is illustrated by the RSD noted between the targeted nodule and the actual PTC tumor focus in the resection specimen.

Clinical, histopathological, and molecular characteristics of papillary thyroid microcarcinoma

BACKGROUND

Papillary thyroid microcarcinoma (PTMC) detection has been increasing explosively with the recent improvement and application of new diagnostic tools. However, the associations between clinical, histopathological, and molecular findings are often not fully evaluated in reaching a decision for the treatment of PTMC.

OBJECTIVE

To retrospectively evaluate the patients diagnosed with PTMC in terms of the clinical and histopathological features and the immunohistochemical findings of specific molecular markers, and thereby provide an association with the disease prognosis for the Korean patients.

DESIGN

We have reviewed the clinical records of patients who underwent surgery for thyroid cancer (during January 2000 to August 2006 interval) at St. Mary's Hospital, Seoul, Korea. The clinical and histopathological characteristics of 217 PTMCs were evaluated cross-sectionally after surgery, and immunohistochemical staining of p53, epidermal growth factor receptor (EGFR), Ki-67, and cyclooxygenase-2 (COX-2) for 87 isolated specimens was performed.

MAIN OUTCOME

The proportions of extrathyroid extension, lymphatic invasion, and lymph node metastasis cited were 31.9%, 19.2%, and 17.8%, respectively. However, distant metastasis was not noted. Fifty-three (27.1%) patients had multiplicity, and 39 patients (20.0%) had bilateral disease. A primary tumor larger than 5 mm was significantly associated with extrathyroid extension, lymphatic invasion, and lymph node metastasis. The absence of EGFR expression shown by immunohistochemical analysis was closely correlated with extrathyroid extension and lymph node metastasis, while the absence of COX-2 expression was associated with multiplicity and bilaterality.

CONCLUSION

Many patients with PTMC had clinical and histopathological poor prognostic factors. The expression of molecular markers, such as EGFR and COX-2, may have a role in the prognosis of PTMC. When considering all of the prognostic factors, a more tailored management approach appears to be necessary for patients with PTMC.